Submission #75237

#	Time	Username	Problem	Language	Result	Execution time	Memory
75237		ainta	Highway Tolls (IOI18_highway)	C++17	100 / 100	375 ms	11420 KiB

highway

#include "highway.h"
#include <cstdio>
#include <algorithm>
#define N_ 151000
using namespace std;
int n, m, Q[N_], head, tail, par[N_], vis[N_], pN[N_], vv[N_];
vector<int>T, E[N_];

void find_pair(int N, std::vector<int> U, std::vector<int> V, int A, int B) {
	int i;
	n = N;
	m = U.size();
	T.resize(m);
	for (i = 0; i < m; i++) {
		T[i] = 0;
		E[U[i]].push_back(V[i]);
		E[V[i]].push_back(U[i]);
	}
	long long L = ask(T);
	int b = 0, e = n - 2, mid, r = n - 1;
	while (b <= e) {
		mid = (b + e) >> 1;
		if (e - b > 60000)mid = 60000;
		for (i = 0; i < m; i++) {
			if (U[i] > mid || V[i] > mid)T[i] = 1;
			else T[i] = 0;
		}
		if (ask(T) == L)r = mid, e = mid - 1;
		else b = mid + 1;
	}
	int root = r;
	Q[++tail] = root, vis[root] = 1;
	par[root] = -1;
	while (head < tail) {
		int x = Q[++head];
		for (auto &y : E[x]) {
			if (!vis[y]) {
				vis[y] = 1;
				Q[++tail] = y;
				par[y] = x;
			}
		}
	}
	for (i = 0; i < m; i++) {
		if (par[U[i]] == V[i])pN[U[i]] = i;
		if (par[V[i]] == U[i])pN[V[i]] = i;
	}
	b = 1, e = tail - 1, r = tail;
	while (b <= e) {
		mid = (b + e) >> 1;
		if (e - b > 60000)mid = 60000;
		for (i = 0; i < m; i++)T[i] = 1;
		for (i = 2; i <= mid; i++) T[pN[Q[i]]] = 0;
		if (ask(T) == L)r = mid, e = mid - 1;
		else b = mid + 1;
	}
	int ed = Q[r];
	int tp = ed;
	while (tp != root) {
		vv[pN[tp]] = 1;
		tp = par[tp];
	}
	b = 1, e = r - 1;
	while (b <= e) {
		mid = (b + e) >> 1;
		for (i = 0; i < m; i++) {
			if(!vv[i])T[i] = 1;
			else T[i] = 0;
		}
		for (i = 2; i <= mid; i++) T[pN[Q[i]]] = 0;
		if (ask(T) == L)r = mid, e = mid - 1;
		else b = mid + 1;
	}
	int st = Q[r];
	answer(st, ed);
}

• Subtask 1: 5 / 5
• Subtask 2: 7 / 7
• Subtask 3: 6 / 6
• Subtask 4: 33 / 33
• Subtask 5: 18 / 18
• Subtask 6: 31 / 31